Concrete preparation with aqueous solution of product from polyether with polymethylene polyphenyl polyisocyanate

Abstract

The structural strength properties of concrete and its resistance to sealing are improved by incorporating into the concrete-forming mixture an aqueous solution obtained by admixing polymethylene polyphenyl polyisocyanates with less than a stoichiometric amount of a polyethylene glycol (MW 600 to 3000) or polypropylene glycol tipped with 15 to 85 percent ethylene oxide (MW 1000 to 3500) and, within a short time of completing the admixture but during the period where said mixture is completely soluble in water, dissolving said mixture in water. Optionally, a difunctional extender is added to the solution so obtained in an amount less than that required to react with all the excess isocyanate groups.

We claim: 
     
       1. An improved process for the preparation of concrete wherein the improvement comprises incorporating into the concrete-forming mixture from about 0.1 parts to about 10 parts by weight, based on the solids content thereof, per 100 parts by weight of concrete-forming mixture, of an aqueous solution which comprises the product obtained by admixing at a temperature in the range of 25° C. to 100° C. (i) a polyether glycol selected from the group consisting of polyethylene glycols having a molecular weight from 600 to 3000 and polypropylene glycols capped with from 15 to 85 percent by weight of ethylene oxide and having a molecular weight from 1000 to 3500, with (ii) a mixture of polymethylene polyphenyl polyisocyanates containing from 25 to 90 percent by weight of methylenebis(phenyl isocyanates) the remainder of said mixture being polymethylene polyphenyl polyisocyanates of functionality higher than 2.0, the proportions of (i) and (ii) being such that there are from 0.1 to 0.99 equivalents of polyol per equivalent of polyisocyanate, and, during the time when the product so obtained is completely soluble in water, admixing said product with water in a proportion of from 1 to 20 parts by weight of said product per 100 parts by weight of water to form a clear aqueous solution. 
     
     
       2. A process according to claim 1 wherein an amount of an extender less than that required to react with all the free isocyanate groups is incorporated into the said aqueous solution. 
     
     
       3. A process according to claim 2 wherein the extender is hexamethylenediamine. 
     
     
       4. A process according to claim 1 wherein the amount of water, in parts by weight, employed to prepare the aqueous solution, if from five to ten times the combined weight of polyether glycol and polyisocyanate. 
     
     
       5. A process according to claim 1 wherein the polyisocyanate employed to prepare said aqueous solution contains approximately 60 percent by weight of methylenebis(phenyl isocyanate) the remainder of said mixture being polymethylene polyphenyl polyisocyanates of higher functionality. 
     
     
       6. A process according to claim 1 wherein the polyisocyanate employed to prepare said aqueous solution contains about 35 percent by weight of methylenebis(phenyl isocyanate) the remainder of said mixture being polymethylene polyphenyl polyisocyanates of higher functionality. 
     
     
       7. An improved process for the preparation of concrete wherein the improvement comprises incorporating into the concrete-forming mixture from about 0.1 parts to about 10 parts by weight based on solids content thereof, per 100 parts by weight of concrete-forming mixture, of an aqueous solution which comprises the product obtained by admixing, at a temperature in the range of about 25° C. to about 100° C., (i) a polyethylene glycol having a molecular weight from 600 to 3000 with (ii) from 2 to 5 equivalents, per equivalent of said glycol, of a mixture of polymethylene polyphenyl polyisocyanates containing from 25 to 90 percent by weight of methylenebis(phenyl isocyanate) the remainder of said mixture being polymethylene polyphenyl polyisocyanates of functionality higher than 2.0, and, during the time when said admixture is completely soluble in water, dissolving said product in water in a proportion of from 1 to 20 parts by weight of said product per 100 parts by weight of water to form a clear aqueous solution. 
     
     
       8. A process according to claim 7 wherein the water employed to prepare the said aqueous solution also contains from 0.01 to 0.5 equivalents, per equivalent of polyethylene glycol, of hexamethylenediamine. 
     
     
       9. An improved process for the preparation of concrete wherein the improvement comprises incorporating into the concrete-forming mixture from about 0.1 parts to about 10 parts by weight based on solids content thereof, per 100 parts by weight of concrete-forming mixture, of an aqueous solution which comprises the product obtained by admixing, at a temperature in the range of about 25° C. to about 100° C., (i) a polypropylene glycol capped with from 15 to 85 percent by weight of ethylene oxide a molecular weight from 1000 to 3500 with (ii) from 2 to 5 equivalents, per equivalent of said glycol, of a mixture of polymethylene polyphenyl polyisocyanates containing from 25 to 90 percent by weight of methylenebis(phenyl isocyanate) the remainder of said mixture being polymethylene polyphenyl polyisocyanates of functionality higher than 2.0, and, during the time when said admixture is completely soluble in water, dissolving said product in water in a proportion of from 1 to 20 parts by weight of said product per 100 parts by weight of water to form a clear aqueous solution. 
     
     
       10. A process according to claim 9 wherein the water employed to prepare the said aqueous solution also contains from 0.01 to 0.2 equivalents, per equivalent of polyisocyanate, of hexamethylenediamine.